The instant invention relates to medical apparatus and more particularly to a self-sealing laterally compressed elastomeric septum which is penetrable by a hypodermic needle or the like and to a surgically implantable infusion port which includes the septum.
Surgically implantable infusion ports have been heretofore available for a number of years, and have generally been found to be effective for dispensing medication in the bodies of patients. One of the most common types of heretofore available infusion ports comprises a rubberized base portion, a metallic housing on the base portion having an interior cavity therein and an opening at the upper end thereof, a penetrable elastomeric septum which is received in sealing relation in the opening in the housing, and a catheter which extends from the interior cavity to the exterior of the housing. In use, an infusion port of this type is normally surgically implanted in a patient so that it is positioned beneath the skin with the upper end of the housing and the penetrable septum facing outwardly, and with the catheter positioned so that it can transmit medication to a predetermined area of the patient's body, such as a large vein. Once an infusion port of this type has been surgically implanted in the body of a patient, the cavity in the housing can be filled with medication by inserting a hypodermic needle through the skin of the patient so that the tip portion of the needle penetrates the septum and passes into the interior cavity and by then dispensing medication in the cavity through the needle. In most instances, after a predetermined amount of medication has been dispensed in this manner, the hypodermic needle is removed, so that the elastomeric septum reseals itself in the area where it was penetrated by the hypodermic needle. However, it has been found that each time the septum of an infusion port of this type is penetrated by a needle, a certain amount of damage is caused to the septum and that after a septum has been repeatedly penetrated, it can lose its ability to reseal itself. It has been further found that when this occurs, it is generally necessary to surgically replace the entire infusion port.
Another type of heretofore available infusion port is disclosed in the Moden et al U.S. Pat. No. 4,710,174. This device is intended to be utilized in a similar manner to that hereinabove set forth, although it is adapted for side entry with a hypodermic needle rather than top entry, such as with the above mentioned device.
The instant invention provides an effective septum which is laterally compressed to enhance the ability thereof to repeatedly reseal itself over a prolonged period of time and an effective infusion port which incorporates the septum. Specifically, the infusion port of the instant invention comprises a housing portion having an interior cavity therein and an access opening in the housing, a septum received in sealing relation in the access opening, and a catheter which extends between the interior cavity and the exterior of the housing for dispensing medication in the body of a patient. The septum of the instant invention is made of a substantially solid elastomeric material and it has an outwardly facing surface thereon. The septum is penetrable by a hypodermic needle by inserting the needle through the outwardly facing surface of the septum. The septum is compressed by between approximately 1% and 30% in a direction which is substantially parallel to the outwardly facing outer surface thereof, and it is preferably compressed by between 5% and 10% in two substantially perpendicular directions, both of which are parallel to the outwardly facing surface of the septum. In one embodiment of the infusion port, the septum is of substantially circular configuration and it is compressed in at least two radially extending directions. In this embodiment, the septum is preferably substantially flat, but it is preferably at least slightly concave prior to being compressed. In another embodiment, the septum comprises first and second layers of elastomeric material, wherein the first layer is operative for applying a compressive force to the second layer in order to maintain the second layer in a compressed disposition.
It has been found that because the infusion port of the instant invention includes a laterally compressed septum, it has an increased effective life as compared to many of the heretofore available infusion ports. Specifically, it has been found that the septum of the infusion port of the subject invention has a substantially increased ability to reseal itself after repeated penetration, and that as a result, the effective life of the septum is substantially increased. Accordingly, the infusion port of the instant invention can normally remain implanted in the body of a patient for an extended period of time before surgical replacement is necessary. It has also been found that the compressed septum of the instant invention can be effectively utilized in a variety of other applications to provide a resealable barrier between two fluids, including liquids and/or gases. For example, the compressed septum can be effectively utilized as a penetrable barrier for dispenser bottles of the type commonly utilized for filling hypodermic syringes.
Accordingly, it is a primary object of the instant invention to provide an effective infusion port having a laterally compressed septum.
Another object of the instant invention is to provide an infusion port comprising a septum having an enhanced ability to reseal itself after being repeatedly penetrated with a hypodermic needle.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.